This invention relates to a tubular structure having a link between two tubular members. More specifically, a tubular structure includes a first tubular member, a second tubular member, and a connector interconnecting the two tubular members, such as by welding.
U.S. Pat. No. 4,660,345 discloses a tubular assembly with a connector assembled by welding a pair of tubular members. In particular, in FIG. 24 welding seams are visible on the tubular assembly. The welding seams are generally positioned along radial lines across the surface of the tubular members to be assembled. During welding, heat is created along these seams and creates a radial expansion of the tube. During cooling, the effects of the expansion may leave the tube with a residual curvature. This residual curvature is difficult to model because it is dependent on the molecular structure of the tube, which is rarely homogeneous. This risk is even more critical when the weld seams do not run over the entire peripheral surface of the tubes, which can cause expansion of one portion of the tube and no expansion of the other portion, thereby creating residual stresses at the intersection of the two portions.
One aspect of the present invention includes an assembly having two tubular members secured by welding a connector that prevents the appearance of curvatures during assembly of the tubular members. For this purpose, the invention has a tubular structure, such as a portion of a vehicle axle, including at least one first tubular member, at least one second tubular member, and a connector interconnecting the first and second tubular members by welding. The connector welds onto one of the two tubular members with at least one welding bead that extends along a generating line of the tubular member. The end of the second tubular member seats against the first tubular member, with the axis of the end of the second tubular member generally in the same plane as the axis of the first tubular member.
In one embodiment, the connector welds onto the two tubular members with at least one welding bead extending along one of the generating lines of each of the two tubular members, with the ends of the two tubular members having a generally circular cross-section.
Thus, the connector securing the two tubular members includes a first welded portion on the second connecting member and a second welded portion on the first connecting member. The first portion of the connector includes a generally V-shaped or U-shaped section, with the ends defining the contact lines between the connector and the end of the second tubular member. The welding seams are carried out along these contact lines. The spacing between the ends are preferably less than or equal to the outside diameter of the circular end of the second tubular member. The second portion of the connector is generally planar, with the end portion having a straight edge that defines a rectilinear contact line between the connector and the first tubular member. The welding seam is produced along this contact line. The connector includes an indexing hole that allows positioning of the connector in relation to a reference point on the first tubular member during assembly by welding the connector on the first tubular member.
In another embodiment, the connector includes two half-shells positioned diametrically on opposite sides of the second tubular member, so that the straight edges of the second portions of the two half-shells sandwich the first tubular member. The second tubular member also includes an indexing hole that allows positioning of the second tubular member in relation to a reference point on the first tubular member or in relation to one indexing hole of one of the two half-shells.
The invention also includes a method of assembling a tubular structure assembly having the above characteristics, including:                a first step of positioning the second portions of the two half-shells diametrically on either side of the first tubular member by a tool pre-positioning itself relative to one reference point belonging to the first tubular member, the tool including two guide pins inserting into the indexing holes of the half-shells,        a second step of welding the weld seams along to the contact lines of the two half-shells on the first tubular member, said contact lines extending along generating lines of the first tubular member;        a third step of positioning the end of the second tubular member between the first portion of the two half-shells relative to one point of reference belonging to the first tubular member or relative to an indexing hole of one of the half-shells, by using a tool including a finger inserting into the indexing hole of the second tubular member;        a fourth step of clamping the two half-shells against the second tubular member; and        
a fifth step of welding the two half-shells on the second tubular member, along the contact lines of the two half-shells, the contact lines extending along the generating lines of the second tubular member.
The invention also relates to an axle of a vehicle wheel having a central portion formed by a tubular structure including at least one of the preceding characteristics.
Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings.